Study On The Low Temperature Conditions Strength Properties Of Cement Mixing Saturated Loess And Bearing Characteristics Of Composite Foundation

At present, most domestic and foreign researches focus on cement mixing saturated loessfoundation reinforcement, but less researches about cement mixing saturated loess foundationreinforcement in saturated loess area, especially for researches about cement mixing soilunconfined compressive strength growth patterns under low temperature curing in water,freezing and thawing cycle, low temperature curing water conservation and indoor watercuring. So, this paper focuses on the unconfined compressive strength growth patterns ofcement mixing saturated loess under low temperature curing in water, low temperature curingin water combined with indoor water curing, and freezing and thawing cycle, the effect ofcement mixing saturated loess strength saturated loess foundation is studied. Based on publicworks equipment operation management maintenance technology research—bidirectionalsoil-cement mixing pile composite foundation reinforced different grades railway saturatedloess foundation research project, to study the cement mixing saturated loess unconfinedcompressive strength growth patterns under low temperature curing in water, low temperaturecuring in water combined with indoor water curing, and freezing and thawing cycle. Soilsamples are selected in the test section, and a large number of indoor tests are conducted,including the cement mixing saturated loess under low temperature curing in water, lowtemperature curing in water combined with indoor water curing, and freezing and thawingcycle. The influences of the fly ash cement dosage (the second ash dosage) and curing age onthe unconfined compressive strength, and the influence of the moisture content on cementmixing saturated loess unconfined compressive strength are studied.By studying on the cement mixing saturated loess unconfined compressive strengthgrowth patterns under low temperature curing in water, low temperature curing in watercombined with indoor water curing, and freezing and thawing cycle, and investigating on thenumerical simulation analysis about composite foundation with cement mixing saturated loesspile, it could mainly draw the following conclusions:(1) Strength formation mechanism of the cement mixing saturated loess is studied underlow temperature curing in water, low temperature curing in water combined with indoor watercuring, and freezing and thawing cycle. The moisture lively of cement mixing saturated loesswill weaken or freeze under low temperature or when water is frozen, and it can’t participatein the hydrolysis of cement hydration, this will slow or even stop the strength increase; (2) Cement mixing saturated loess adopts low temperature curing in water, and lowtemperature curing in water combined with indoor water curing, the unconfined compressivestrength grows with the second ash dosage and age, but the strength lower than indoor watercuring with the same time, this indicates curing temperature will influence the growth of thecement mixing saturated loess unconfined compressive strength, and low temperatureenvironment causes the strength of the cement mixing saturated loess loss; The moisturecontent has negative effect to the strength;(3) Cement mixing saturated loess during the process of freezing and thawing cycle,with no supply water curing before freezing, the unconfined compressive strength increaseswith the second ash dosage and age, but compared with low temperature curing in water andindoor water, the strength is lower, thus it explains strength loss; So during freezing andthawing cycle, the cement mixing saturated loess has certain ability to resist freezing andthawing cycle after it reaching an early strength; Its strength will decreases with the increaseof moisture content, and the higher moisture content, the more serious the damage;(4) By studying the cement mixing saturated loess unconfined compressive strengthgrowth patterns under low temperature curing in water, low temperature curing in watercombined with indoor water curing, and freezing and thawing cycle, it knows that under thecondition of low temperature in winter, cement mixing soil foundation reinforcement couldn’tbe constructed in low temperature curing in water combined with indoor water curing;(5) By studying settlement characteristics of single pile composite foundation and grouppile composite foundation of cement mixing pile and roadbed subsidence, it is concluded thatsingle pile composite foundation settlement and the body stress increases with the loadincreases gradually, and the biggest stress occurs at the top of the pile; Group pile compositefoundation settlement grows with the load increases gradually, while the pile body stressincreases firstly and then decreases with the load increases, and the maximum pile body stressoccurs in some parts rather than at the top of the pile; the settlement of roadbed overall centerdecreases with the increase of depth.